We all know the drill: you’re driving along quite happily when suddenly a siren alerts you to a fast-approaching police car or ambulance.

Human drivers, accustomed to such sudden arrivals, (usually) know to clear a path for the oncoming vehicle.

But for the developers of self-driving cars, emergency vehicles pose a special challenge.

In the longer term, connected vehicle technologies will let emergency vehicles communicate directly with the cars around them, alerting other road users to their presence.

Before that, however, self-driving cars will have to respond like human drivers – listening out for emergency sirens, scanning for flashing lights and being ready to move out of the way.

To help prepare them, self-driving car developer Waymo has been teaching its minivans to recognise different types of emergency vehicles, including fire trucks, ambulances, and police cars and motorbikes.

All this is possible because our self-driving minivans are outfitted with custom-built self-driving sensors, including an audio detection system designed in-house.

The company recently held an emergency vehicle testing day for its self-driving minivans, aimed at building a library of sights and sounds to help the vehicles learn how to respond safely when they meet an emergency vehicle.

Waymo says that its self-driving minivans can already hear twice as far as they used to be able to, thanks to newer sensors.

Now, the developer is also training them to detect which direction sirens are coming from, in order to make ‘smarter and safer decisions’.

If an emergency vehicle approaches from behind, says Waymo, its self-driving minivans might pull over. If the siren is coming from up ahead, they may give way at an intersection.

“All this is possible because our self-driving minivans are outfitted with custom-built self-driving sensors, including an audio detection system designed in-house,” said Waymo in a blog post detailing its testing.

“Not only have we improved the way our cars hear sirens, but our vehicles can see emergency vehicles and their flashing lights even further and clearer with our custom vision system, radars, and LiDARs.”

Thanks to this technology, Waymo believes its vehicles can also be trained to recognise emergency vehicles that they haven’t encountered before.

In the meantime, it’ll still be down to human drivers to react when flashing lights appear in the rear-view mirror.

But before too long, if Waymo’s efforts are anything to go by, spotting and reacting to emergency vehicles could be one more driving task your car handles for you.

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